console and grub run at a higher resolution by default, to disable that set GRUB_TERMINAL=console in /etc/default/grub

they reinvent the scrollbar (called overlay scrollbar), it now hides itself when not moused over and other weird stuff, very annoying, hard to hit a target with the mouse that you can't see, new scrollbar is only in a few apps, not in all Gtk stuff

fix scrollbar with: sudo apt-get purge overlay-scrollbar.*

new default music player seems to be Banshee and no longer Rhythmbox (no obvious import/export to transfer media)

it takes way longer then before from the time the mouse is visible to when the Gnome panels show up on boot

XVideo and OpenGL on ATI is broken, the video always gets displayed on top, even if the window is in the background

Firefox constantly resets my "middleclick paste" setting to false

Overall this upgrade so far looks pretty horrid, some of the changes might make sense on a touchscreen device, but none of the interface changes really make any sense on a big desktop screen, this is doubly bad considering that the new interface is what you get on a regular dist-upgrade, not something you have to manually enable. Good news however that all changes so far seem to be revertible.